Classifying Rocks 5.1



Vocab:

texture- the look and feel of the rock's surface
grains-particles of minerals or other rocks
igneous rock-forms from the cooling of molten rock
sedimentary rock- forms when particles of other rocks or the remains of plant's and animal's are pressed and cemented together
metamorphic rock- formed when an existing rock is changed by heat, pressure, or chemical reactions

Outline



How Geologists Classify Rocks
  • rocks are important for building
    • rocks form mountains, hills, valleys, beaches, and the ocean floor
  • earth's crust is made of rock
    • geologists collect and study to classify rocks
Texture
  • texture is the look and feel of a rock's surface
  • grains give the rock its texture
Grain Size
  • usually grains of rocks are visible
  • rocks that are fine-grained are so small you can't see them
Grain Shape
  • some grains look like sand
  • others look like seeds or exploding stars
  • some grains are rounded
  • some grains are jagged